Long-term Experience and Outcomes of Programmatic Antiretroviral Therapy for Human Immunodeficiency Virus Type 2 Infection in Senegal, West Africa

Abstract

Background: Programmatic treatment outcome data for people living with human immunodeficiency virus type 2 (HIV-2) in West Africa, where the virus is most prevalent, are scarce.

Methods: Adults with HIV-2 initiating or receiving antiretroviral therapy (ART) through the Senegalese national AIDS program were invited to participate in this prospective, longitudinal observational cohort study. We analyzed HIV-2 viral loads, CD4 cell counts, antiretroviral drug resistance, loss to follow-up, and mortality. We also examined changes in treatment guidelines over time and assessed progress toward the Joint United Nations Programme on HIV/AIDS (UNAIDS) 90-90-90 targets for HIV-2.

Results: We enrolled 291 participants at 2 sites for 926.0 person-years of follow-up over 13 years. Median follow-up time was 2.2 years per participant. There were 21 deaths reported (7.2%), and 117 individuals (40.2%) were lost to follow-up, including 43 (14.7%) who had an initial visit but never returned for follow-up. CD4 counts and HIV-2 viral suppression (< 50 copies/mL) at enrollment increased over calendar time. Over the study period, 76.7% of plasma viral loads for participants receiving ART were suppressed, and median CD4 gain was 84 cells/μL in participants' first 2 years on study. Since the UNAIDS 90-90-90 strategy was published, 88.1% of viral loads were suppressed. Fifteen percent of patients experienced virologic failure with no known resistance mutations, while 56% had evidence of multiclass drug resistance.

Conclusions: Participants in the Senegalese national AIDS program are initiating ART earlier in the course of disease, and more modern therapeutic regimens have improved outcomes among those receiving therapy. Despite these achievements, HIV-2 treatment remains suboptimal, and significant challenges to improving care remain.

Keywords: 90-90-90; HIV treatment; HIV-2; antiretroviral therapy; viral suppression.

Figure 1.

Enrollment CD4⁺ T-cell count and viral load suppression for participants receiving antiretroviral therapy (ART) through the Senegalese national program, by study enrollment year. Median (interquartile range) CD4 count (cells/μL) of study participants (left y-axis, solid line) and proportion of study participants with viral load suppression (< 50 copies/mL, right y-axis, dashed line) as a function of enrollment year. Number of participants enrolled per year, percentage of subjects enrolling already receiving ART, and number of participants for whom CD4 count and viral load data are available are listed below the plot.

Figure 2.

Viral load (VL) suppression and CD4⁺ T-cell counts among participants receiving antiretroviral therapy (ART) through the Senegalese national program. Rates of VL suppression (< 50 copies/mL) (A) and median (interquartile range) CD4 counts (cells/μL) (B) are shown as a function of time on study. Data shown are from enrollment, month 1 postenrollment, and trimesterly visits thereafter. Due to variability in interval between visits, data are binned within 2 months before and after target visit date. Number of participants with a visit occurring within 2 months of the annual anniversaries of their enrollment, and number of data available for each variable at those visits, are shown between panels.

Figure 3.

Viral load suppression for participants receiving antiretroviral therapy (ART) through the Senegalese national program, by calendar year. Proportion of viral load results < 50 copies/mL from ART-experienced (> 6 months) study participants, shown as a function of calendar year of the visit. Dashed line indicates 90%. Number of eligible visits and percentage of visits with viral load data available are listed below the plot.

Figure 4.

Kaplan-Meier estimation of study retention. The probability of participant retention on study, where both loss to follow-up (blue hash marks) and death (red hash marks) are considered as failures, is plotted. Participants were considered lost to follow-up if they had not come to a follow-up visit for > 1 year, and were censored at last visit date. Participants who were reported dead were censored at date of death if known, or date of last clinic visit if not. All remaining participants were censored at study closure. Number of participants at risk is shown below. Insets show actual time to death among 21 participants who died (A) and time to loss to follow-up among 117 participants (B).